Oh it's just a little standing position. Sounds easy enough, right ladies? Well, to most men, the idea of having sex standing up is a slippery, pride-greased slope towards repeating the phrase, "I'm so sorry," over your naked heap of a body and his own rapidly blue-ing balls. It's not like he's going to say no. If he wants to have sex with you, he'd swear he could bench press twice his body weight right up until he passed out from the 500 lbs of barbell he just dropped on his own chest. You think he's going to tell you he doesn't have the strength to hold you up for more than five seconds?
Also, "Suspended Congress" is just about the most unappealing name for a position in the history of sex.
Why it's Dangerous:
Anne Hooper warns in her Keep It Simple Kama Sutra Series that this position should not be attempted by men "that have even the inkling of a bad back!" (Exclamation-mark totally included.) Now there's a bit of medical history he's going to willingly volunteer when you've just asked him to turn you into a human sex swing.